JPH0376261B2 - - Google Patents

Description

Detailed Description of the Invention: "Industrial Application Field" The present invention relates to a hydraulic booster used in a brake booster or a clutch booster, and more specifically, it is capable of reducing input shaft loss stroke at the initial stage of operation. The present invention relates to a loss stroke reduction device for a hydraulic booster.

"Prior Art" A hydraulic booster is normally operated in conjunction with a power piston that is slidably fitted into a housing, a power chamber formed at one end of the power piston, and an input shaft. The chamber is equipped with a control valve that advances the power piston by introducing hydraulic pressure corresponding to the input applied to the input shaft into the power chamber, and the small input is multiplied by the hydraulic pressure corresponding to the input introduced into the power chamber. It is now possible to output

"Problems to be Solved by the Invention" The control valve is configured to communicate the power chamber with the hydraulic pump when the input shaft moves forward, and switch the power chamber into communication with the reservoir when the input shaft moves backward. In order to ensure a sufficient flow path area during each operation, it is necessary to increase the lift amount of the control valve, that is, the shift amount of the input shaft. However, if the shift amount of the input shaft is increased, a large shift amount is required to move the input shaft forward from the non-operating state and switch the flow path of the control valve, which causes a large loss of stroke at the beginning of input shaft operation. It has the disadvantage of becoming.

"Means and Effects for Solving the Problems" In view of such circumstances, the present invention is generally provided in this type of hydraulic booster, which is attached to the inner circumferential surface of the hole of the power piston, We focused on the fact that it is equipped with a retaining member that allows the power piston to operate, and also contacts the tip of the piston to prevent it from retreating beyond a predetermined amount, thereby preventing the tip from falling out of the hole of the power piston. A retaining member is provided so as to be movable forward in the operating direction of the power piston, and a retaining member is provided in the housing of the hydraulic booster so that the retainer comes into contact with the retaining member when the hydraulic booster is not in operation. A stopper member is provided to hold the member and the input shaft in contact with the member at a required forward position relative to the power piston, thereby making it possible to reduce stroke loss of the input shaft at the initial stage of operation with a simple configuration.

``Example'' Hereinafter, an example in which the present invention is applied as a brake booster will be described. In the figure, a housing 1 of the hydraulic pressure booster has a roughly cylindrical shape, and a hole is formed in the shaft portion of the housing 1. A power piston 3 is slidably fitted into the inside of the piston 2. Also housing 1
A plug 4 that closes the right end of the hole 2 fixed to the
A hole 5 is bored on the same axis as the hole 2, and an input shaft 6 is connected to the brake pedal (not shown).
are slidably fitted.

A master cylinder housing 7 is arranged on the same axis and connected and fixed to the left end of the housing 1, and a rod 8 provided at the left end of the power piston 3 is interlocked with the piston 9 of the master cylinder. ing. The power piston 3 is biased to the right by a spring 11 loaded between the retainer 10 provided in the master cylinder and the power piston 3 and held at the non-operating position shown in the figure. A power chamber 12 is formed between the right end portion and the plug 4.

The piston 9 of the master cylinder is provided with a seal portion 13, with the front side of the seal member 13 serving as a primary chamber 14 and the rear side serving as a secondary chamber 15. These primary chamber 14 and secondary chamber 15 are connected to a passage 18 via passages 16 and 17 formed in the housing 7 of the master cylinder, respectively.
This passage 18 communicates via a conduit with a reservoir of a master cylinder (not shown).

The tip of the input shaft 6 is slidably and loosely fitted into a stepped hole 25 with a bottom formed in the right end shaft portion of the power piston 3, and the tip of the input shaft 6 and the stepped hole 25 of the power piston 3 A hydraulic pressure corresponding to the magnitude of the input applied to the input shaft 6 is applied to the power chamber 7 into the hole 25.
A control valve 26 is provided to introduce the inside. This control valve 26 includes a check valve 27 provided in the stepped hole 25 of the power piston 3 and a check valve 27 provided in the input shaft 6.
7 forcibly open.

The valve body 29 of the check valve 27 is the power piston 3
Seated from the left side of the figure by a spring 31 on a valve seat 30 provided in The chamber 33 is the power piston 3
It communicates with a pump or an accumulator (not shown) through a passage 34 formed in the outer peripheral surface of the power piston 3, an annular groove 35 formed in the outer peripheral surface of the power piston 3, a passage 36 formed in the housing 1, and a filter 37 provided in the middle of the passage 36. Pressure oil is constantly introduced into the pressure chamber 33.

On the other hand, the shaft portion of the annular pin 28 is connected to an axial passage 40 and a radial passage 41 formed in the input shaft 6.
It communicates with the annular groove 42 formed in the plug 4 through the passageway 43 formed in the plug 4, a passageway 44 formed in the housing 1, and a conduit 45 connected thereto to the reservoir 46 of the pump (not shown). It's communicating. Further, the outer circumferential portion of the annular pin 28 is located between the outer circumferential surface of the large-diameter tip portion 6a of the input shaft 6 and the inner circumferential surface of the stepped hole 25 of the power piston 3. It also communicates with the power chamber 12 through the annular groove 51 of the power piston 3 and between the inner circumferential surface of the stepped hole 25 of the power piston 3 and the outer circumferential surface of the left portion of the plug 4. The left end of the valve body 29 of the check valve 27 from the seal member 32 communicates with the outer peripheral portion of the annular pin 28 via an axial passage 47 formed in the power piston 3.

However, on the inner circumferential surface of the hole 25 of the power piston 3, there is a retainer located on the right side of the large-diameter tip portion 6a of the input shaft 6 to prevent the large-diameter tip portion 6a from falling out of the hole 25. A member 50 is provided.
This retaining member 50 is fitted into an annular groove 51 formed on the inner circumferential surface of the hole 25 and is movable in the axial direction. In the free state, the input shaft 6 is biased to the right in the figure by the spring 52 elastically mounted between the power piston 3 and the input shaft 6, and the large diameter portion 6a at the tip of the input shaft 6 is pressed against the retaining member. 50 and the retaining member 50
comes into contact with the right end of the annular groove 51 to prevent the large diameter portion 6a from falling out of the hole 25.

In this free state, the annular pin 28 is attached to the valve seat 3.
The valve body 29 is greatly retreated from the valve body 29 seated at the position 0, and the outer periphery of the annular pin 28 and the shaft portion, that is, the power chamber 12 and the reservoir 46 can be communicated with each other through a large flow area.

Further, the left end of the plug 4 is extended in the axial direction and serves as a stopper member 4 for the retaining member 50, and in the non-operating state shown in the figure,
The right end surface of the retaining member 50 is the stopper member 4.
At the same time, the left end surface abuts on the large diameter portion 6a at the tip of the input shaft 6, and the input shaft 6
At the same time, the retaining member 5
0 comes into contact with the left end of the annular groove 51, and also restricts the rightward movement of the power piston 3.

In this non-operating state, the input shaft 6 is advanced relative to the power piston 3 by the width of the annular groove 51 compared to the free state, and therefore the input shaft 6
The annular pin 28 provided in the check valve 27 comes to be close to the valve body of the check valve 27. As a result, when the brake pedal is depressed and the input shaft 6 moves to the left from the non-operating state shown in the figure, the tip of the annular pin 28 immediately comes into contact with the valve body 29 of the check valve 27 to operate the control valve 26. Therefore, the loss stroke of the input shaft 6 at the initial stage of operation is reduced.

In the above configuration, in the illustrated non-operating state, the power chamber 12 communicates with the shaft portion of the annular pin 28,
Further, since the shaft portion of the annular pin 28 communicates with the reservoir 46 as described above, the oil pressure within the power chamber 12 is maintained at substantially zero.

In this state, when the brake pedal is depressed and the input shaft 6 is moved to the left from the non-operating state shown in the figure,
The tip of the annular pin 28 immediately touches the valve body 2 of the check valve 27.
9 and is sealed, thereby cutting off communication between the power chamber 12 and the reservoir 46. When the input shaft 6 continues to move to the left, the valve body 29 is separated from the valve seat 30 by the annular pin 28, and the pressure oil that is constantly introduced into the pressure chamber 33 is released from the outer circumference of the annular pin 28. It is introduced into the power chamber 12. At this time, pressure oil is also supplied to the left end side of the valve body 29 through the axial passage 47 formed in the power piston 3, so that the valve body 29 is moved to the left side by the pressure oil introduced into the power chamber 12. It will never be done.

When pressure oil is introduced into the power chamber 12, the pressure oil acts on the power piston 3 and moves the power piston 3 to the left against the spring 11.
It acts on the input shaft 6 to allow the driver to sense the brake reaction force. In the intermediate load state, the power chamber 1
The hydraulic pressure introduced into the brake fluid pressure booster 2 is controlled to a pressure corresponding to the magnitude of the input applied to the input shaft 6, that is, the depression force of the brake pedal, similarly to the conventional brake fluid pressure booster of this type.

Next, when the brake operation is released, that is, in a free state, the input shaft 6 retreats and the valve body 29 seats on the valve seat 30, stopping the supply of pressure oil to the power chamber 12. is ring pin 2
Since the piston 3 is connected to the reservoir 46 through the shaft portion of the piston 8, the pressure inside the power chamber 12 decreases, and the power piston 3 is retracted to the right by the elastic force of the spring 11. At this time, as described above, the retaining member 50 comes into contact with the large-diameter tip portion 6a of the input shaft 6 and also comes into contact with the right end of the annular groove 51, and the annular pin 28 is seated on the valve seat 30. It is largely set back from the valve body 29, allowing the power chamber 12 and the reservoir 46 to communicate with each other through a large flow path area.

Then, the retaining member 50 is attached to the stopper member 4.
When the input shaft 6 comes into contact with and is stopped, the retreat of the input shaft 6 is simultaneously restricted, but since the retaining member 50 moves relatively within the annular groove 51, the power piston 3 continues to retreat, and the retaining member 50 When it comes into contact with the left end of the annular groove 51, the rightward movement of the power piston 3 is also restricted. In this state, as described above, the input shaft 6 is advanced relative to the power piston 3 by the width of the annular groove 51, so that the loss stroke of the input shaft 6 at the beginning of the next operation is reduced.

In this embodiment, the retaining member 50 conventionally provided in the power piston 3 is movably fitted into an annular groove 51 formed in the power piston, and the plug 4 conventionally provided in the housing 1 is fitted movably into an annular groove 51 formed in the power piston. The retaining member 50
Since only the stopper portion 4 is in contact with the stopper portion 4, the loss stroke of the input shaft 6 can be reduced at low cost without complicating the structure compared to conventional devices.

"Effects of the Invention" As described above, according to the present invention, it is possible to obtain the effect that the loss stroke of the input shaft at the initial stage of operation can be reduced with a simple configuration.

[Brief explanation of drawings]

The figure is a sectional view showing one embodiment of the present invention. 1...Housing, 3...Power piston, 4
...Plug (stopper member), 5...hole, 6...
Input shaft, 6a... large diameter tip, 12... power chamber,
26... control valve, 50... retaining member, 51...
...Annular groove.

Claims (1)

[Claims] 1. A power piston slidably fitted into the housing, a power chamber formed at one end of the power piston, an input shaft whose tip end is slidably fitted into a hole formed in the power piston, and the above power piston. a control valve that is operated by the forward motion of the input shaft and causes the power piston to advance by introducing hydraulic pressure into the power chamber according to the input applied to the input shaft; A retaining member is attached to the input shaft and allows the input shaft to move forward, and also comes into contact with the tip of the input shaft to prevent it from moving back more than a predetermined amount, thereby preventing the tip from falling out of the hole of the power piston. In the hydraulic booster, the retaining member is provided so as to be movable forward in the operating direction of the power piston, and the housing is provided with a retaining member that contacts the retaining member when the hydraulic booster is not in operation. 1. A loss stroke reduction device for a hydraulic booster, comprising a lever stopper member and a stopper member that holds the input shaft in contact with the lever at a required forward position with respect to the power piston.